HANDBOOK 


FOR THE 

LONGUE-VUE BINOCULAIRE A PRISMES 

(STEREOSCOPIC TELESCOPE) 

(CAMPAGNE-MODELE 1917) 


(NOTES ON_ THE PRISMATIC BINOCULAR TELE¬ 
SCOPE, MODEL 1917). 


Prepared byjhe American Expeditionary Forces. 



Army War College 

February, 1918. 










War Department 
Document No. 759 
Office of the Adjutant General. 


n7 of 3* 

oct 23 1929 



WAR DEPARTMENT, 
Washington, February 25, 1918. 

The following notes on the “Prismatic Binocular Telescope, 
Model 1917,” which have been adopted by the American Expe¬ 
ditionary Forces as standard, are published for the information and 
guidance of all concerned. 

(062.1. A. G. O.) 

By order of the Secretary of War, 

JOHN BIDDLE, 

Major General, Acting Chief of Staff. 

Official: 

H. P. McCAIN, 

The Adjutant General. 


TABLE OF CONTENTS 


Handbook for the Longue-Vue Binoculaire a Primes— 

(Campagne-Modele 1917). 5 

General Description 5 

Instructions for use. 6 

Section 1—Setting up—Observation of terrain. 6 

Section 2—Preparatory operations ,. 7 

Section 3—Direction and control of fire. 

Transportation . 

Up-keep . 

Accessories ..... 

Optical and other data. 

Annexe—To read deflection in terms of plateau and tambour 


00 00 O) Oi 05 H 













HANDBOOK 


FOR THE 

LONGUE-VUE BINOCULAIRE A PRISMES 

(CAMPAGNE MODELE 1917) 


GENERAL DESCRIPTION. 

The “longue-vue binoculaire a prismes” (stereoscopic tele¬ 
scope) is specially intended for the observation of targets and for 
the direction and control of fire. It is particulatly suited for ob¬ 
servation at small and meduim ranges. 

The “Campagne modele 1917’’ is used with batteries provided 
with sights graduated in mils (6400 mils — 360 degrees), namely, 
the following: 75 m/m. guns, 65 m/m. mountain guns, 14 and 145 
L. modele 1916,155 L. modele 1877-1914 and modele 1917 Schneider 
155 C. modele 1915 Schneider, 220 m/m. Schneider howitzer, etc. 

The principal features of the instrument are as follows: 

1° The telescope can be used in either of the two positions 
shown in fig. 1 and 2; in the latter the ratio between the distance 
between object glasses and the inter-ocular distance is as much as 
10.6 (for an observer whose inter-pupillary distance is 65 m/m.) 
and consequently the relief-effect is considerably increased. 

2° The magnification is 12; the illumination is greater than 
that of the 1909 pattern prism binocular and enables use of the 
telescope in conditions of low visibility. 

3° The right-hand side telescope is fitted with a micrometer 
(fig. 4) which can be adjusted as desired by turning a milled ring. 

4° The telescope is mounted upon an elevation movement D 
carrying a sight clinometer C; it is used on a stand fitted with an 
azimuth movement (see fig. 1, 2 and 3). 

The sight clinometer enables the measurement of angles of sight 
in mils (6400 mils = 360 degrees. 

The azimuth movement comprises two dials—an upper dial, 
carrying elevation movement and telescope which can be moved 
over a lower dial by turning milled head T of a tangent screw. 
Without upsetting the relative positions of upper and lower dials 
the whole instrument can be rotated by turning milled head S of 
lower tangent screw. 



6 


There are two graduations: 

(1) On the lower dial a continuous clockwise graduation (*) 
from 0 to 6400 mils, used in conjunction with black index on upper 
dial. Each division is worth 100 mils and intermediate 
values are read on the left-hand side graduation of the tangent 
screw drum. Each graduation of the drum graduation is worth 
1 mil, and it is read in conjunction with the black index mark (the 
one engraved on smooth ground). 

(2) A second graduation on upper dial; this, in conjunction 
with the right-hand side graduation on tangent screw drum being 
intended for use specially with 75 m/m. and 65 m/m. mountain bat¬ 
teries when angles are measured in terms of “plateau” and “tam¬ 
bour” of the gun-sight. (See Annexe). 

INSTRUCTIONS FOR USE 

§ 1.—Setting up—Observation of Terrain. 

To set up the instrument.—Remove stand and azimuth move¬ 
ment from their case (see that clamp C is tight). Loosen clamps 
of tripod legs and adjust sliding portions to desired height; press 
each leg well into the ground. Free the ball-and-socket joint R 
of the tripod by turning clamping nut G in counter-clockwise di¬ 
rection and bring the bubble to the centre of the spherical level 
H; then clamp ball-and-socket joint by turning nut G in clockwise 
direction. 

Remove the telescope from its case. The elevation movement 
D will be found folded against the left-hand side body; without 
attempting to move it from this position fit it onto the pivot of 
azimuth movement (see that spur on azimuth movement engages 
with slot on elevation movement). Clamp elevation movement 
on azimuth movement by means of lever L. 

Loosen, if necessary, the hinge-clamp S of the telescope and 
place the body-tubes either in the “periscopic position” (fig. 1) 
or in the “stereoscopic position” (fig. 2). 

Tighten hinge clamp S and fit the ray shades over the object 
glasses and, if necessary, the yellow glasses over the eye-pieces. 
Adjust for focus and inter-ocular distance, as below: 

To focus the instrument.—Each eye-piece is focussed separate¬ 
ly. To focus, for example, the right-hand side telescope shut the 
left eye and observe a distant object with the right eye; turn milled 
collar until the definition is at its best. The graduations marked 
on eye-pieces are in dioptries 

To adjust for inter-ocular distance.—Both eye-pieces having 
been focussed, proceed as follows in order to adjust for inter-ocular 
distance: Direct the telescope on a uniformly illuminated surface 
by turning milled head P of elevation movement; loosen the hinge- 

(*) Corresponding to the graduation of gun sights with 75 m/m. guns, 65 m /m. 
mountain guns and the Schneider materiel mentioned on page 5. It should be noted 
that in the Schneider gun sights the index is fixed and the graduation movable,where¬ 
as in the 75 m/m. gun sight the “plateau” is fixed and the index movable. Butin both 
cases an increase in deflection is left deflection. 



clamp S; grasp body-tubes with the two hands and adjust the dis¬ 
tance apart until the two fields are superposed. Tighten hinge- 
clamp S. 

Scales in millimeters enable the observer to note the inter¬ 
ocular distance best suited for his eyes—in either the periscopic 
or the stereoscopic positions. 

To lay on a determined point without making angular measure¬ 
ments.—Loosen clamp C fixing azimuth movement to stand. The 
telescope can then be turned freely in a horizontal plane. Elevate 
or depress as required by milled head P. 

§ 2.—Preparatory Operations. 

To measure an angle of sight (in mils).—Slacken clamp C and 
lay roughly for direction; tighten clamp C and adjust accurately 
by milled head S. Bring the centre of the cross of the micrometer 
on the target by means of elevation movement P. 

Turn the clinometer on the telescope hinge until a “catch” is 
felt; bring the bubble of the clinometer level in the centre of its 
run by turning milled head U. 

Read the angle in hundred of mils on the divided sector V (placed 
at the side of the clinometer) and the intermediate values on the 
drum Z. Black figuring corresponds to positive angles of sight, 
red figuring to negative angles. The black and red figures of the 
drum Z correspond to the figures of same color on the sector V. 

To measure the horizontal angle between two points (in mils).— 
If the two points come at the same time in the field of the tele¬ 
scope make use of the horizontal scale of the micrometer (see fig. 
4) each division of which is worth 5 mils. 

In the other case proceed as follows—set the azimuth move¬ 
ment to zero by turning milled head T so that the zero on the lower 
dial coincides with index X on upper dial and the zero of the tan¬ 
gent screw drum coincides with index Y. Lay roughly on the left- 
hand side point by loosening clamp C, tighten clamp C and lay 
accurately by turning milled head S of general movement. Now 
lay on the right-hand side point by turning milled head T of 
relative movement (*). Read angle measured on lower gradu¬ 
ation and tangent screw drum (indexes X and Y respectively). 

To measure deflection for a given target.—Set the azimuth move¬ 
ment to zero and lay on target, then lay on aiming point by turn¬ 
ing milled head T. Read off deflection—this can be expressed 
either as a true angle as indicated on continuous graduation (0— 
6400 mils—see paragraph headed (To measure the horizontal 
angle between two points) or in terms of “plateau” and “tambour” 
(see Annexe). 

To lay a gun parallel to a given direction (by reciprocal observa¬ 
tions).—1° Using gun-sights with graduation divided into 4 quad- 


(!) When it is desired to measure an angle of several hundred mils it is quicker to 
throw tangent screw out of action by pressing pallet W right down. The upper dial 
will then turn freely over the lower dial. Before using slow motion see that the screw 
has properly engaged—but do not attempt to force it home—turn milled head T and 
screw will soon fill into gear. 



s 


rants and with ‘‘zero position’’ at 100 mils. (75 m/m. and 65 m/m 
mountain batteries). Station instrument about 50 metres from 
gun and lay it in the given direction (target or expected direction 
of fire) by using clamp C and milled head S, the instrument being 
set to zero. Now lay instrument on gun-sight pillar and read in 
terms of “plateau” and “tambour” the deflection which must be 
given to the gun (see Annexe). Lay the gun with this deflection 
on the centre of the instrument. 

2° Using gun-sights with continuous graduations divided in 
6400 mils with zero position at 0 mils. Station instrument about 
50 metres from gun; set the instrument at 3200 mils and lay in the 
given direction by using clamp C and milled head S. Now lay 
instrument on gun-sight pillar using milled head T; read off the 
angle as indicated by continuous graduation. Lay the gun with 
this deflection on the centre of the instrument. 

3° Using gun-sights with graduation in two halves divided in 
3200 mils in the same direction and with zero position at 1000 mils. 
Station instrument about 50 metres from gun; set the instrument 
at 4200 mils and lay in the given direction, using clamp C and milled 
head S. Now lay instrument on gun-sight pillar using milled head 
T; read off the angle as indicated by instrument. Subtract 3200 
if the reading obtained is greater than or equal to 3200. Lay the 
gun with this deflection on the centre of the instrument. 

§ 3.— Direction and Control of Fire. 

To determine the height of burst (in mils).—Make use of the 

vertical scale of the micrometer—divided every 5 mils. The dis¬ 
tance between the dotted line and the zero graticule represents 
3 mils and is equal to height of the top of the cross above centre 
lines—this angle is the “hauteur type” (the normal height of burst) 
for 75 m/m. guns. 

Correction of deflection.—The instrument being laid in direc¬ 
tion of target, bring the point of burst onto the vertical graticule 
of micrometer by turning milled head T. The deflection of gun 
must be increased (or diminished) by the angle by which the in¬ 
strument reading has increased (or diminished). 

Change of target.—The instrument being laid on the old target, 
direct telescope on the new target turning milled head T. The 
deflection of the gun must be increased (diminished) by the angle 
by which the instrument reading has diminished (increased). 

TRANSPORTATION. 

To put the instrument and tripod back in their cases.—Remove 

ray shades and yellow gla ses, put these in the places provided for 
them in the case. Loosen clamp S and fold the two bodies to the 
left so that the elevation movement S comes into contact with the 
left body. Do not tighten up the clamp S. Separate telescope 
from azimuth movement after having pressed down the clamping 
lever L; turn the instrument round and put it in its case, object 
glasses first and turned towards the hinge of the case. Fasten in 


9 


the instrument by closing hinged front of case, close lid and fasten 
strap. The telescope in its case is carried on the back like a hav¬ 
ersack. 

To put the tripod and azimuth movement in their cases.—Fold up 
tripod and insert it in its case legs first so that feet are in contact 
with bottom of case. Close lid and do up fastening strap. The 
tripod in its case is carried across the shoulder. 

UP-KEEP. 

It is essential that the instrument should be very carefully 
handled so as to avoid shocks and falls. Cleaning of internal parts 
and dismounting of the dials or telescope are strictly forbidden. 
If necessary the instrument should be returned for repairs to the 
“Service Geographique de l’Armee”. External parts only are to 
be cleaned. In cleaning a lens, never rub it with a cloth or any. 
thing which might grease or scratch the glass; breath on the sur¬ 
face and dry immediately by rubbing gently with a piece of fine 
dry linen which is not fluffy. Repeat this until the vapor condenses 
regularly and evaporates concentrically. 

ACCESSORIES. 

These include reinforced leather case with strap: 

2 yellow moderating glasses in pockets of the case; 

1 waterproof cloth case with leather lining, containing tripod 
and azimuth movement. 


OPTICAL AND OTHER DATA. 


Magnification.. 

Real field....about 

Dia. of exit pupil___ 

Weight of telescope without case. 

- - - with case.. 

- of tripod and azimuth in case 

movement...... 


12 

67 mils 
4 mm. 25 
4,8 to 5,4 kgs. 
7,3 to 7,9 kgs. 

7,7 kgs. 

































































































" 




















































































































































11 


ANNEXE. 

TO READ DEFLECTION IN TERMS OF PLATEAU 
AND TAMBOUR. 


When the stereoscopic telescope is used with 75 mm. batteries 
and set up close to the battery, by using the quadrant graduation 
on upper dial and the two indexes Y, W of the tangent screw drum 
the commands can be given in terms of “plateau” and “tambour”. 

“It should be noted that when the instrument is at zero, i. e., 
when index X is in line with zero division of lower graduation, 
the reading in terms of plateau and tambour is “plateau : 0”, “tam¬ 
bour :100”. 

To read in terms of “plateau”.—One quadrant of upper dial is 
divided into 8 sectors marked P L 0, P L 2, etc., P. L. 14. As the 
optical axis of the telescope passes through the four quadrants of 
the “cercle fictif de pointage” (fig. 5) the quadrant on the upper 
dial passes successively over 4 arrow-shaped indexes which fall on 
the 0,16,32 and 48 marks of lower (continuous) graduation, whence 
the rule: 

The “plateau” number is the number of the sector on which one 
of the indexes falls ( x ) (see example fig. 6). 

To read in terms of “tambour.”—Each sector of the divided 
quadrant comprises a smooth and a ruled portion. In reading 
in terms of “plateau”, note in which of these two portions the 
index falls and read the tangent screw drum accordingly, i. e., use 
either reader Y on smooth ground or reader W on ruled ground 
(see example fig. 6). 


C 1 ) When laying a gun for direction by “reciprocal sighting” (page 7), the proximity 
of the gun renders the consideration of the quadrant useless; in this case, it will be seen 
that the indexes of the gun-sight and the telescope are necessarily brought into oppo¬ 
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Fig. 1. — Periscopic position . 











































- 

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Fig. 2 — Stereoscopic position 




























































































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Fig. 3. 












































- 




* 







Figure 4- — Micrometer. 


The center of the cross indicates the optical axis of the 
instrument. 

Each division of vertical and horizontal scales is worth 5 
mils. 

The length of any arm of the cross is worth 3 mils. The top 
of the cross and the dotted line above the zero graticule facili¬ 
tate the obtention of the normal height of burst of 3 mils, 
when the center of the cross coincides with the base of the 
target. 




























































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* ■ 











Figure 4. 



CERCLE FICTIF DE POINTAGE 


(THEORETICAL SIGHT DIAL) 


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Figure 5. 




















































































